What is the original Japanese?

千日の稽古を鍛とし萬日の稽古を鍊とす. Translated from the original Japanese by Spartan Surfers.

A thousand days of practice forge you. Ten thousand refine you.

Miyamoto Musashi, The Book of Five Rings, Water (closing)

The source

"A thousand days of practice forge you. Ten thousand refine you." Miyamoto Musashi said it in The Book of Five Rings, Water (closing). Translated from the original Japanese by Spartan Surfers.

"千日の稽古を鍛とし萬日の稽古を鍊とす"

Original Japanese, The Book of Five Rings, Water (closing). Japanese: Miyamoto Musashi (Kinkodo, 1909), NDL digital text.

Who said it

Miyamoto Musashi (c. 1584–1645). Undefeated swordsman who wrote The Book of Five Rings in a cave a few weeks before he died.

Questions

Who said "A thousand days of practice forge you. Ten thousand refine you."?: Miyamoto Musashi (c. 1584–1645). Source: The Book of Five Rings, Water (closing).
What is the original Japanese?: 千日の稽古を鍛とし萬日の稽古を鍊とす. Translated from the original Japanese by Spartan Surfers.